L4: Autonomic ganglia and functions of sympathetic NS to head and neck

Question 1

What is the origin of Sympathetic Supply to the Head and Neck?

Answer 1

LHCs of first and second thoracic segments

Question 2

What is the relay of the LHCs of the first and second thoracic segments?

Answer 2

Superior cervical ganglion (SCG)

Question 3

What are the parts affected by the sympathetic supply to the head and neck?

Answer 3

• Eye
• Salivary glands
• Skin
• Cerebral blood vessels

Question 4

Effect of sympathetic supply to the eye

Answer 4

a. Contraction of dilator pupillae ms→ dilatation of pupil (mydriasis)
b. Contraction of smooth ms in eyelids (Tarsal ms) leading to elevation of upper and lowering of lower eyelids→ widening of palpberal fissure.
c. Contraction of Muller ́s ms (behind eyeball) → exophthalmos.
d. Relaxation of ciliary ms→ ↓ convexity of the lens→ helps the eye to see far objects.
e. Vasoconstriction (V.C.) of blood vessels of lacrimal glands and trophic secretion.

Question 5

Effect of sympathetic supply to the salivary glands

Answer 5

a. Vasoconstriction (V.C.) of salivary gland blood vessels.
b. Trophic secretions: little, viscous, concentrated secretion; poor in water and rich in enzymes.
c. Contraction of myoepithelial cells surrounding salivary acini leading to squeezing of salivary secretion outside.

Question 6

Effect of the sympathetic supply to the skin

Answer 6

a. V.C or vasodilatation (V.D.) of skin blood vessels, but VC is more powerful.
b. Hair erection due to contraction of piloerector muscle.
c. Sweatsecretion.

Question 7

Effect of the sympathetic supply to cerebral blood vessels

Answer 7

Mild vasoconstriction (V.C.).

Question 8

What is the definition of Horner’s syndrome?

Answer 8

It is a group of signs which result from interruption sympathetic to the head and neck.

Question 9

What are the causes of Horner’s syndrome?

Answer 9

a. Lesion in T1 and T2 segments.

b. Lesion in SCG disease or experimentally by section in the cervical sympathetic chain.

Question 10

What is the site of Horner’s syndrome?

Answer 10

Manifestations occur at the same side of the lesion.

Question 11

What are the signs of Horner’s syndrome?

Answer 11

a. Ptosis → dropping of upper eyelids due to paralysis of superior tarsal ms.
b. Miosis → constriction of the pupil due to paralysis of dilator pupillae ms.
c. Enophthalmos → sinking of eye ball into orbit due to paralysis Muller’s ms.
d. Anhydrosis → absence of sweat secretion leading to dryness affected side of the face.
e. Vasodilatation of skin blood vessels, due to loss of sympathetic vasoconstrictor tone, so the skin becomes red and warm.